{"id":"GHSA-wjpq-6766-7f5j","summary":"CoreWCF: Unix Domain Socket PosixIdentity transport accepts connections that skip the security upgrade","details":"### Impact\nA CoreWCF service hosted on Unix Domain Sockets with the PosixIdentity client credential type (UnixDomainSocketBinding with Security.Mode = TransportCredentialOnly and Security.Transport.ClientCredentialType = PosixIdentity) does not require the client to perform the application/unixposix stream upgrade before dispatching messages.\n\n### Patches\nFixed in CoreWCF v1.8.1 and v1.9.1\n\n### Workarounds\nRestrict filesystem access to the UDS socket file using owner/group/mode (e.g. chmod 0660 plus a dedicated group) so that only the POSIX users who are already authorized to invoke the service can connect at all. This makes the missing-upgrade behaviour equivalent to the operating system’s filesystem permissions instead of relying on framing-layer identity checks.\nAvoid relying on ServiceSecurityContext.PrimaryIdentity for authorization decisions, or back it up with an authentication-required authorization policy that rejects anonymous principals.","aliases":["CVE-2026-54776"],"modified":"2026-06-19T21:11:29.955022Z","published":"2026-06-19T20:46:52Z","database_specific":{"cwe_ids":["CWE-306"],"severity":"MODERATE","github_reviewed":true,"github_reviewed_at":"2026-06-19T20:46:52Z","nvd_published_at":null},"references":[{"type":"WEB","url":"https://github.com/CoreWCF/CoreWCF/security/advisories/GHSA-wjpq-6766-7f5j"},{"type":"PACKAGE","url":"https://github.com/CoreWCF/CoreWCF"}],"affected":[{"package":{"name":"CoreWCF.UnixDomainSocket","ecosystem":"NuGet","purl":"pkg:nuget/CoreWCF.UnixDomainSocket"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.8.1"}]}],"versions":["1.5.0","1.5.0-preview1","1.5.1","1.5.2","1.6.0","1.7.0","1.8.0"],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/06/GHSA-wjpq-6766-7f5j/GHSA-wjpq-6766-7f5j.json"}},{"package":{"name":"CoreWCF.UnixDomainSocket","ecosystem":"NuGet","purl":"pkg:nuget/CoreWCF.UnixDomainSocket"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"1.9.0"},{"fixed":"1.9.1"}]}],"versions":["1.9.0"],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/06/GHSA-wjpq-6766-7f5j/GHSA-wjpq-6766-7f5j.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N"}]}